1. Field of the Invention
The present invention relates to cosmetic compositions comprising proteolytic enzymes which remove the stratum corneum of the skin, thus enhancing the penetration of other active components, including biological components, into the underlying layers of the skin.
2. Description of the Related Art
Exfoliants are compounds which remove the dead cell layer (stratum corneum) of the skin, and are used, for example, in the treatment of aging skin (removal of wrinkles), photodamaged skin, acne, dry skin, and other skin conditions. Currently commercially available cosmetic formulations for topical use typically include the following exfoliants: alpha hydroxy acids (AHAs) (e.g. glycolic acid and lactic acid), beta hydroxy acids (BHAs) and retinoids, which may cause adverse reactions including skin irritation, erythema, blistering, particularly in individuals with sun damaged skin, and chronic or unusually high photosensitivity, especially among ethnic groups having darker skin tones.
Thus, there is a need for cosmetic preparations comprising exfoliants which are effective and non-irritating, especially in individuals with sun damaged skin. The present invention addresses this need.
Performed embodiments of the present invention provide compositions for topical use, including but not limited to lotions, gels and creams, comprising an enzyme in combination with at least one, at least two, at least three or more, biological additive. Said enzyme is preferably papain, derivable from papaya, and is capable of removing the stratum corneum when applied thereto. The biological additives are preferably selected from the group consisting of Echinacea angustifolia extract, mimosa tenuiflora extract, hydrocotyl (centella asiatica) extract, gingko biloba extract, tea tree oil, Matricaria chamomila (chamomile) extract, Hypericum perforatum extract, and Aloe barbedensis extract, catemdiele extract, but may be any biologically-active biologic. The pH of the compositions described herein are preferably greater than about 4.5 or, more preferably, greater than 5.0, and are most preferably about 7.0.
Also described is a method for enhancing penetration of at least one, two three, or more biological additive into the skin, comprising applying to said skin a formulation comprising said at least one biological additive and an enzyme capable of removing at least a portion of the stratum corneum. The enzyme is preferably papain, is more preferably papain linked to a high molecular weight polymer, and is preferably papain linked to high molecular weight polyacrylic acid. Also provided is a method for treating an individual having skin exhibiting at least one condition selected from the group consisting of aging skin, photodamaged skin, acne, and dry skin, comprising: diagnosing a individual having said skin, applying to said skin a formulation comprising said at least one biological additive and an enzyme capable of removing at least a portion of the stratum corneum.
Preferred embodiments of the present invention provide effective, non-irritating topical cosmetic formulations comprising an enzyme which promotes removal of at least a portion of the stratum corneum of skin and therefore promotes deeper penetration of other compounds contained within the composition into subsurface skin. Thus, such an enzyme acts as an exfoliant, removing only portions of the dead cell layer of the skin, causing no damage to the underlying living cell layers. Currently available exfoliants, including AHAs, BHAs and retinoids tend to cause adverse topical reactions including but not limited to skin irritation, erythema and blistering. The topical enzymatic compositions disclosed herein have a pH that is more basic than the pH of skin, and preferably have a pH of about 7.0, thus contributing to their non-irritating properties relative to currently commercially available exfoliants.
One preferred enzyme is papain, an enzyme obtained from unripe papaya. One particularly preferred form of papain is Linked-Papain(trademark) (papain carbomer, as described in CTFA, the International Cosmetic Ingredients Dictionary) in which papain is covalently immobilized to 1% polyacrylic acid (900,000 daltons), commercially available from Collaborative Laboratories, 3 Technology Drive, East Setauket, N.Y. 11733). In a preferred embodiment, the enzyme is present in the formulation in an amount between about 1% and 6%, more preferably between about 2% and 5%, most preferably about 4% by weight. The ability of papain to act as an exfoliant allows enhancement of penetration of any desired medicinal agent beneficial to the skin, such as, for example, biological additives (e.g, botanicals and herbals) and moisturizers. The activity of papain is greatest at a pH of 6, although the enzyme retains about 75% of its activity between pH 5 and 7. The cosmetic compositions preferably have a pH that is basic relative to the pH of skin (the pH of which typically ranging from approximately 4.5 to approximately 5.0), and preferably have a pH of about 7.0.
The papain compositions described herein may be formulated for topical application with pharmaceutically acceptable carriers using methods well known in the cosmetic and pharmaceutical arts, including gels, creams, ointments, emulsions, dispersions, salves, pastes, lotions and the like. These formulations may additionally comprise one or more emulsifiers, humectants (e.g., glycerin or glycerol, sorbitol, and the other known polyols), skin conditioning agents (e.g., propylene glycol, sweet almond oil, apricot kernel oil), surfactants (e.g. ceteth-20), colorants such as staining dyes and pigments (e.g, calcium, barium and aluminum lakes, iron oxides, titanium dioxide and mica), antioxidants (i.e., ascorbic acid, tocopherols, ascorbyl palmitate, thiodipropionic acid), viscosity-enhancing agents (e.g., cetearyl alcohol, polyethylene glycol), vitamins, minerals, emollients, skin conditioning agents, biological additives (e.g. botanicals or herbals), sunscreens (e.g. octyl methoxycinnamate, butyl methoxydibenzolylmethane, oxybenzone), pH adjusters, solvents, germicides (e.g., antibiotics, Tricolsan), preservatives (e.g., BHT, methylparaben, ethylparaben, propylparaben, butylparaben) and fragrances (e.g., strawberry extract, mangifera indica). It will be appreciated by those of skill in the art that particular compounds may be properly classified in one, or two or more of the above-listed classifications of compound types.
The compositions may also include one or more biological additives, such as botanicals or herbals. As used herein, the term xe2x80x9cbiological additivexe2x80x9d indicates any compound obtained from a natural source, including plants, animals, bacteria and yeast, which has a medicinal or otherwise beneficial effect when topically applied to the skin. Examples of biological additives include oil of Melaleuca alternifolia, oil of Lavandula angustifolia, Carica papaya extract, Echinacea angustifolia extract, Mimosa tenuiflora extract, Hydrocotyl (centella) asiatica extract, gingko biloba extract, oil of Melaleuca alternifolia (tea tree oil), Matricaria chamomila (chamomile) extract, Hypericum perforatum extract, Aloe barbedensis extract, and the like. The biological sources for xe2x80x9cbiological additivexe2x80x9d may also include, but are not limited to the following: Aloe Vera, Aloe Barbedensis; Arnica, Arnica Montana; Bladderwrack (seaweed), Fucus Vesciculosis; Birch, Betula Alba (Pendula); Chamomile, Matricaria Chamomila (Chamomila Recutita); Marsh Mallow, Althea Officinalis; Meadow Sweet, Spirea Ulmaria (Filipendula); Mint/Lemon Balm, Melissa Officinalis; Mimosa, Mimosa Tenuiflora; Myrrh Tincture, Commiphor Myrrha; Neem, Melia Azadirachta; Nettle (stinging), Urtica Dioica; Papaya, Carica Papaya; Propolis (bee glue), Propolis Cera; Raspberry, Rubis Idaeus; Red Poppy, Papaver Rhoeas; Rose Hip (dog rose), Rosa Carima; Rosemary, Rosemarinus Officinalis; Sage, Salvia Officinalis; St. Johns Wort, Hypericum Perforatum; Strawberry, Fragaria Vesca; Thea Sinensis (green tea), Camelia Sinensis; Walnut, Juglans Regia; Witchhazel (dist/extr), Hamamelis Virginiana; Yarrow, Achillea Millefolium; Wild Yam, Dioscorea Villosa; Hawthorn, Crataegus Monogina/Oxyantha; Herma (black/rod), Lawsoma Ehemus; Hops, Humulus Lupulus; Horse Chestnut, Aesculus Hippocastanum; Horse Tail, Equisitum Arvense; Ivy, Hedera Helix; Linden/Lime Tree Blossoms, Tilia Argentea Cordata; Madder, Rubia Tinctorum; Marigold, Calendula Officinalis; Centella Asiatica, Centella Asiatica Urban (hydrocotyl Asiatica); Carrot (roots), Daucus Carota; Comfrey (Allantoine), Symphytum Officinale; Coneflower (Echinacea), Echinacea Angustifolia; Cucumber, Cucumis Sativus (Frucus Cucumis); Fenugreek, Trigonella Foenum Greacum; Gingko, Gingko Biloba; Ginseng, Panax Ginseng; Great Burdock, Radix Bardanea/Arctium Lappa; Tea Tree Oil, Oil of Melaleuca Alternifolia; Colts Foot, Tussilago Farfara; Clover, Trifolium Pratense; Speedwell, Veronica Officinalis. 
Further biological additives, along with the biological or medicinal properties of the biological additives described herein and of other known biological additives are know to those of skill in the art. References, including encyclopedias and treatises, known to those of skill in the art, that described such biological additives, along with the biological or medicinal properties of the biological additives described herein, include: Guentherxe2x80x94The Essential Oils, Van Nostrand; Int. Cosmetic Ingredient Dictionary, Vol 1 and 2, C.T.F.A. 1995; Int. Cosmetic Ingredient Handbook, C.T.F.A. 1995; British Herbal Pharmacopoeia, British Herbal Medicine Assoc., 1983; Clinical Applications of Ayurvedic and Chinese Herbs, K. Bone, Phytotherapy Press, 1996; A Handbook of Chinese Healing Herbs, D. Reed, Shambala, Boston, 1995; Echinaceaxe2x80x94Nature""s Immune Enhancer, S. Foster, Healing Arts Press, Rochester, 1991; Encyclopedia of Herbs, D. Brown, RD Press, 1995; Encyclopedia of Medicinal Plants, A. Chevalier, Dorling Kingers Ley, 1996; L""Angelicaxe2x80x94Herbal Extracts; Cosmetochemxe2x80x94Herbasol Extracts. These references are incorporated herein in their entirety.
Emulsifiers contemplated for use include but are not limited to monoacyl glycerol, such as glyceryl monoalkanoates, glyceryl monoalkenoates, diacyl 1,2- or 1,3-disubstituted) glycerol, such as glyceryl dialkanoates, glyceryl dialkenoates, polyglyceryl esters, stearic acid, cetyl alcohol, and sorbitan stearate.
Other examples of biological additives include, but are not limited to, Carica papaya extract, Echinacea angustifolia extract, tea tree oil, Mimosa tenuiflora extract, Hydrocotyl (centella asiatica) extract, gingko biloba extract, Matricaria chamomila (chamomile) extract, Hypericum perforatum extract, Aloe barbedensis extract, and the like. A particularly preferred biological additive is tea tree oil. In a preferred embodiment, one or more biological additives is present in the formulation in a combined amount of from about 1% to 10% by weight, more preferably from about 2% to 8% by weight, and most preferably from about 4% to 6% by weight.
In a preferred embodiment, one or more skin conditioning agent(s) is present in the formulation in a combined amount of from about 1% to 20% by weight, more preferably from about 5% to 10% by weight, and most preferably from about 6% to 9% by weight.
In another preferred embodiment, one or more emollients or humectants is present in the formulation in a combined amount of from about 1% to 10% by weight, more preferably about 2% to 8% by weight.
One or more viscosity increasing agents may be present in the formulations in an amount from about 2% to 10% by weight, preferably about 5% by weight.
One or more antioxidants may also be present in a combined amount of between about 0.1% and 5% by weight, preferably between about 0.5% and 2% by weight.
In another preferred embodiment, one or more emulsifying agents is present in a combined amount of between about 1% and 20% by weight, more preferably between about 5% and 10% by weight.
In another preferred embodiment, one or more antioxidants, preservatives and fragrances is present in the compositions in minor amounts, preferably between about 0.05% and 5% by weight, more preferably between about 0.1% and 2% by weight.
Preferably, the compositions and formulations are directly applied to the skin once per week, once per day, twice per day or three times per day. Alternatively, the compositions and formulations may be applied directly to the skin less frequently or only on specific occasions, for example after a sunburn when the skin is peeling, to achieve certain of the benefits described herein. The quantity and extent of application will vary with the particular result desired or condition to be treated. Such preferred application will vary from about 1 mg per cm2 skin per day to 50 mg per cm2 skin per day, massaged into the skin, as will be appreciated by those of skill in the art, depending on the severity and the condition to be treated.